There was a third airline with Argonauts in the early 60s, Aden Airways
The only airline purchasers of new Argonauts were BOAC and the two Canadian majors, Trans Canada and Canadian Pacific. It was when they disposed of the type that smaller carriers took them (generally as a cheaper alternative to a DC-6). Aden Airways would have been one such, in fact BOAC had a minority shareholding in them, so a natural to get rid of unwanted equipment to !
Possibly the saddest one was G-ALHG, one of a few sold by BOAC to British Midland, which was involved in the Stockport air crash in 1967 on approach to Manchester Ringway, operating a return IT charter from Spain. My elder brother had just started with the Stockport police and was one of the first on the scene. He still remembers the passengers beating on the inside of the windows before everything was consumed by fire.